Can a methanol synthesis tower be pressurized with carbon dioxide gas?
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Some units do not have nitrogen and would like to use carbon dioxide gas for pressurization. Please discuss whether it is possible to use carbon dioxide gas for pressurization after the methanol catalyst has been installed
The gas pressure must not exceed 16 bar
It is not allowed to use carbon dioxide gas for pressurization.
No, after the catalyst is loaded, if carbon dioxide is used for pressurization, it is difficult to ensure that the partial pressure of carbon dioxide in the tower does not exceed the specified limit during the heating and reduction process (it is generally kept below 6%; for some catalysts used abroad, this limit is 20%). If the carbon dioxide level exceeds this limit, it will affect the structure of the copper grains in the catalyst during the heating and reduction process, thereby significantly impacting the catalyst’s activity.
It really won’t work; by using reaction gas to apply pressure, you’re accelerating the process of crushing the catalyst into powder!
The critical pressure of carbon dioxide is 7.4 MPa, and its critical temperature is 31°C; it would be fun if some dry ice were accidentally released from a tower
Answer: No. In coal-to-methanol synthesis, the pressure in the reactor is generally controlled at 5.6 MPa, with a carbon dioxide concentration of 6%; it cannot be too high, as this will lead to increased side reactions of the catalyst and the formation of more impurities such as paraffins.